Overview

  • Girls know more words than boys
    Eriksson et al, 2012; Frank et al, 2016
  • First-born children know more words than later-born children
    Goldfield & Reznick, 1990
  • Children from higher SES families know words
    Fernald, Marchman, & Weisleder, 2013


  • Children from higher SES families receive more language input
    Hart & Risley, 1995


  • Vocabulary at 25 months predicts cognitive and linguistic abilities at 8 years
    Marchman & Fernald, 2008

Do individual words carry demographic signal?

Data

Data

  • Sex
    • Assigned female at birth
    • Assigned male at birth
  • Birth order
    • First-born
    • Second-born
    • Third-born or later-born
  • Maternal education
    • Below Secondary
    • Secondary (~high school degree)
    • College and Above (~college degree)

Data

Data

Data

Analysis

For a language and demographic:

produces ~ age + birth_order + (age + birth_order | item)
  • fixed effect for each demographic in each language
  • random effect for each item for each demographic in each language
  • coding scheme gives difference between adjacent levels

Results

Results

Results

Results

Results

Results

Results

Results

Results

Results

Sex

Results

Birth order

Results

Maternal education

Takeaways

  • Individual words are learned differentially by sex, birth order, maternal education
  • Avoid bias in test design by excluding demographically-linked items
  • Demographic differences in vocabulary size emerge from both quantity of speech and specific content differences

Part of larger work on variability and consistency in language learning
langcog.github.io/wordbank-book

All data and code available at
github.com/langcog/wordbank-book